Basic Investigation of Fe-Pt Magnetic Alloys to Crown and Bridge Prosthodontics.

我们设计和研究了新的可摘冠和桥。分别用Fe-Pt-Nb磁性合金作外盖和磁性不锈钢作内盖，用牙科铸造法制备冠桥，利用磁力增强冠桥的物理强度。本研究的目的是检查Fe-Pt-Nb磁性合金的适用性外盖牙科铸造。第一个实验是研究钛包埋料和模具温度的差异对Fe-Pt-Nb磁性合金的影响。第二个实验是研究添加元素如Si和Nb对Fe-Pt-Nb磁性合金的影响。最后一个实验是研究磁化方式对Fe-Pt-Nb磁性合金吸引力的影响。结果表明：1.通过对Fe-Pt-Nb磁性合金表面粗糙度和磁性能的测定，钛包埋料（Titavest CB）和铸型温度（200-600 ℃）是牙科铸造Fe-Pt-Nb磁性合金的最佳工艺条件; 2. Si的加入量大于0.1（摩尔%）时，可改善Fe-Pt-Nb磁性合金的表面粗糙度，减少铸造缺陷; Si的加入量小于0.2（摩尔%），Nb的加入量大于0.5（摩尔%）时，可获得良好的磁性能。3.冠型（沿沿着冠轴磁化，Fe-39.5Pt-0.65Nb-0.1Si（mol %））的磁吸力平均为536 gf。该值足以保持可摘冠和新娘的使用，但这些合金的适应精度与吸引力和机械性能之间的关系需要进一步研究。

We have designed and studied new removable crowns and bridges. The crowns and bridges are separately prepared by dental casting with Fe-Pt-Nb magnetic alloys for outer caps and magnetic stainless steel for inner caps, respectively, so that magnetic force reinforce their physical strengh. The purpose of this study was to examine the applicability of Fe-Pt-Nb magnetic alloys to outer caps by dental casting. The first experimentation was to investigate effects of differences in titanium investments and the mold temperature on Fe-Pt-Nb magnetic alloys. The second experimentation was to investigate effects of additive elements such as Si and Nb on Fe-Pt-Nb magnetic alloys. The last experimentation was to investigate effects of magnetizing nethods on attractive forces in Fe-Pt-Nb magnetic alloys. The results were as follows :1.Measuring surface foughness and magnetic properties, titanium investment (Titavest CB) and the mold Temperature (200-600ﾟC) were optimum condition for dental casting of Fe-Pt-Nb magnetic alloys.2.The addition of Si 0.1 (mole%) over improved the surface roughness and decreased the casting defect, and the addition of Si 0.2 (mole%) below and of Nb 0.5 (mole%) over could produce the excellent magnetic properties. Therefore, it was conducted that the optimal composhition was Fe-39.5Pt-0.65Nb-0.1Si (mole%).3.The attractive force which was observed with crown-type (magnetized along the crown axis, Fe-39.5Pt-0.65Nb-0.1Si (mole%)) showed 536gf on the average. This value is enough to retain removable crowns and brides for dental use.Further study is needed to elucidate the relationship between the adaptation accuracy and the attractive force as well as mechanical properties of these alloys.